Community Digest

Top new questions this week:

How did games like Doom offer free trials? What was packaged in their free trial software packages?

I remember that Doom had a free trial version where you can play the first episode but the other two you have to buy. There are other games that did that as well. If I understand it, in order to do ...

asked by Michael Stachowsky 26 votes
answered by Raffzahn 66 votes

Did computer games for Commodore 64 really take "25 minutes" to load "if everything went alright"?

In the Swedish-language song "Nostalgi" by Markoolio from 2003, some of the lyrics go: My first computer had 64 kB you surfed on the water, and that's that The computer games were loaded ...

commodore-64 cassette-tape game-cartridge  
asked by Kommendåre 64 24 votes
answered by Michael Graf 54 votes

Where and when did the ".s" suffix for assembly-language source files originate?

The closest I was able to find on StackOverflow is What are .S files?, in which no answerer addresses why we use .s for assembly. (And .S for preprocessor/macro assembly; and gcc -S to produce ...

assembly unix file-format compilers file-system  
asked by Quuxplusone 15 votes
answered by Stephen Kitt 12 votes

Is the NeoGeo capable of raster effects?

The Neo Geo has incredibly powerful sprite based hardware, but can it do raster effects? Raster effects are where changes to the graphics hardware registers are made mid frame, usually timed to be in ...

asked by user 8 votes
answered by Jean-François Fabre 11 votes

Why was there no 32bit or 64bit versions of M68000 & 65xx line of CPUs?

I don't understand why western design centre made the 65816 a 16bit upgrade to the 6502 but commodore semiconductor group/MOS technology didn't make their own variant & why neither company made ...

6502 motorola-68000 m68k 65816  
asked by 6502Assembly4NESgames 7 votes
answered by Liam Proven 22 votes

What specific factor(s) made Thomas Watson, Jr. (of IBM) so enthusiastic about early electronics?

One of my favourite computer history books is Stan Augarten's "Bit by Bit", which has an author-approved scanned copy at In it, the author makes ...

history ibm mainframe  
asked by Mark Morgan Lloyd 6 votes
answered by another-dave 5 votes

VAX 11/780 16MB memory board - what was the physical size?

I'm trying to get a feel for what it looked like when you designed a computer to have a lot of memory chips stuffed into it. To that end, I found this:

hardware memory dec vax  
asked by rwallace 5 votes
answered by another-dave 4 votes

Greatest hits from previous weeks:

Why was BASIC built into so many operating systems?

There are a lot of retro-computers with BASIC as an integral part of the operating system. The IBM 5100 was one of the first computers with a separate memory space for BASIC, followed by the Commodore ...

operating-system basic  
asked by wizzwizz4 83 votes
answered by blubberdiblub 69 votes

Why not use fractions instead of floating point?

Considering all those early home computers, the ZX Spectrum, the Galaksija, the VIC-20, the Apple I/II/III, and all of those, they all have some 8-bit CPU which does integer arithmetic and no floating ...

software floating-point  
asked by OmarL 47 votes
answered by dirkt 99 votes

Where did the free parameters of IEEE 754 come from?

It's clear where many of the design decisions of IEEE 754 floating point come from. For example, the binary format maximizes efficiency on binary hardware. And 32 and 64 bits for single and double ...

history floating-point  
asked by rwallace 36 votes
answered by phuclv 57 votes

Is it true that Netscape Navigator eventually became Mozilla Firefox?

Is it really the case that Mozilla Firefox is a modern day version of Netscape Navigator?

history netscape  
asked by Neil Meyer 33 votes
answered by Stephen Kitt 59 votes

Why would a NES game use an undocumented 1-byte or 2-byte NOP in production?

Reading the NESdev wiki page on CPU unofficial opcodes, I see a few games use an undocumented 2-byte NOP instuction in production: Puzznic, F-117A Stealth Fighter, and Infiltrator use $89 #i. Beauty ...

programming nes assembly 6502 software-development  
asked by JAL 90 votes
answered by LOIS 16192 115 votes

Is it safe to turn on a 40-year old TRS-80?

My father is a retired programmer. When I was in high school in the late 1970s, he purchased a TRS-80 model 1 (on which I learned to program in BASIC). At some point in the early 1980s it, together ...

hardware trs-80  
asked by John Coleman 62 votes
answered by tofro 55 votes

Why did the Apple IIe make a hideous noise if you inserted the disk upside down?

When I began high school in 1987 all the computers in the lab were Apple IIe desktop computers. A question has haunted me since then: if you inserted a floppy disk "upside down" the Apple IIe would ...

apple-ii floppy-drive  
asked by Snack_Food_Termite 29 votes
answered by supercat 115 votes

Can you answer these questions?

advice for retrieving functions and tables from intel 8061/8065 bin file (reverse engineering) from Ford EECV ECU

I have under my disposal some Ford EECV bin files and my goal for the next few weeks is to retrieve the functions and tables and plot them out before going onto DIY hardware . . Does anyone know which ...

intel rom disassembly  
asked by j tay 2 votes

What was the specific function of the relay which captured Grace Hopper's famous "bug"?

Computer pioneer Grace Hopper often recounted the story of her team finding the first physical computer bug: While she was working on a Mark II Computer at Harvard University in 1947, her associates ...

history debugging  
asked by DrSheldon 3 votes

MIPS Encoding of blez/bgtz vs bltz/bgez

In the MIPS architecture, blez/bgtz and bltz/bgez are encoded differently: blez/bgtz are encoded as: [BLEZ/BGTZ: 6 bits] [RS: 5 bits] [0: 5 bits] [OFFSET: 16 bits] bltz/bgez are encoded as: [REGIMM: 6 ...

cpu mips  
asked by secondperson 3 votes
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